1. Field
The present disclosure is related to an organic light emitting diode display.
2. Description of the Related Art
An organic light emitting diode display includes two electrodes and an organic light emitting layer positioned therebetween. Electrons injected from a cathode electrode and holes injected from an anode electrode are combined with each other in the organic light emitting layer to form excitons. Light is emitted while the excitons discharge energy.
The organic light emitting diode display includes a plurality of pixels each including an organic light emitting diode formed of the cathode, the anode, and the organic light emitting layer. A plurality of thin film transistors and at least one capacitor for driving the organic light emitting diode are formed in each pixel. The plurality of thin film transistors includes a switching thin film transistor and a driving thin film transistor.
The driving transistor controls a driving current to the organic light emitting diode, and all driving transistors of the plurality of pixels should have the same current magnitude in response to the same applied voltage, thereby having the same driving range.
However, emission efficiency varies depending on a kind of the organic emission layer used in a plurality of pixels such that a current-luminance ratio, where luminance depends on the current flow in each pixel, is different. That is, the current-luminance of the red pixel and the green pixel is higher in comparison to the blue pixel such that the luminance for the same current is brighter. That is, the red pixel and the green pixel are more sensitive to the luminance depending on the current, in comparison to the blue pixel.
In this case, a variation is easily generated in the driving range of the driving transistors by a distribution on the manufacturing process, and in this case, a color variation is easily generated in the red pixel or the green pixel having the sensitive luminance depending on the current, and particularly, the color variation may be recognized at a low gray level.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the disclosure and therefore it may contain information that does not form prior art.